Paphiopedilum species plants, which know with specific flower shape, gorgeous color, and long ornamental period, have great ornamental and economic value. The classification of the genus is controversial. The diversity and correlation analysis of 27 phenotypic traits were carried out by investigating 29 species of Paphiopedilum, followed by cluster analysis based on the principal components of phenotypic traits. The results showed that the phenotypic variation of Paphiopedilum were rich in diversity. The genetic diversity index (H'') on 17 quantitative characters arranged from 0.7834 to 2.0318. The flower length (FL) and flower width (FW) showed the genetic diversity index higher than 2.0, while flower number (FN) was observed with lower genetic diversity index (less than 1.0). The variation range of genetic diversity index on 10 quality characters was 0.5098-1.1241. The diversity indexes of petal shape (PS) and Lip main color (LMC) were the highest (both >1.0), and the lowest value was observed on staminode bottom concave (SBC) and anther type (AT). From the results of diversity analysis, it can be seen that 29 species of Paphiopedilum have large differences in phenotypic traits among species, with rich diversity. The coefficients of variation (CV) of 17 quantitative traits ranged from 18.22% to 59.09%, and those of the petal length/petal width (PL2/PW) and peduncle length (PL) exceeded 50%. These results showed that the interspecific phenotypic characters of Paphiopedilum palustratum were dispersed greatly. Correlation analysis revealed the relevance and complexity among the phenotypic characters of Paphiopedilum. The principal component analysis suggested five principal components (eigenvalues >1.0) with a cumulative contribution rate of 84.176%. The characters and indexes of flower organs largely contributed to the phenotypic diversity. Cluster analysis suggested six groups of these Paphiopedilum species, being largely coincident with previous classifications except the presence of minor differences.